London: Oil production from the western Libyan fields of Sharara and Wafa has been blocked by armed protesters, reducing output by 252,000 barrels per day (bpd), a source at the National Oil Corporation (NOC) said on Tuesday.

NOC declared force majeure on loadings of Sharara crude from the Zawiya oil terminal in the west of the country and Wafa condensate loadings from the Mellitah terminal.

Supplies were stopped by the shutdown of pipelines leading from the fields to Zawiya refinery and port, a Libyan oil source said. The identity of the group was not immediately clear and there had been no claim of responsibility, he said.

The shutdown at Sharara, which had been producing about 220,000bpd, began on Monday, a day after the Wafa shutdown, the NOC source said.

There was no official comment from the NOC.

The stoppage threatens a partial revival of Libyan output after years of disruptions due to conflict, political divisions and local protests. Pipelines and ports have repeatedly been blocked by groups demanding salary payments or other funding.

National production has still more than doubled since last year to reach about 700,000bpd. Three eastern oil ports were reopened in September, and Sharara resumed operations in December when a two-year pipeline blockade was lifted.

Production remains far below the 1.6 million bpd that Opec member Libya pumped before the 2011 uprising in the North African nation. NOC has set ambitious output recovery goals.

NOC said last week it hoped to raise production from Sharara to nearly 300,000bpd, and that it was targeting national output of 800,000 by the end of April.

Austrian oil firm OMV, one of the foreign partners in Sharara, was due to load a 600,000 barrel cargo of Sharara crude from Zawiya on board the Sea Vine tanker later this week.

The booking for the tanker has been cancelled, a Libyan port source with knowledge of the shipment told Reuters.

OMV did not immediately respond to a request for comment.

The oilfield is operated by a joint venture between NOC and a consortium of Repsol, Total, Statoil and OMV.